National and Subnational estimates for the United States of America

Identifying changes in the reproduction number, rate of spread, and doubling time during the course of the COVID-19 outbreak whilst accounting for potential biases due to delays in case reporting both nationally and subnationally in the United States of America.

Table of Contents


Expected daily cases by region


Figure 1: The results of the latest reproduction number estimates (based on estimated cases with a date of infection on the 2020-03-20) in the United States of America, stratified by state, can be summarised by whether cases are likely increasing or decreasing. This represents the strength of the evidence that the reproduction number in each region is greater than or less than 1, respectively.

National summary

Summary (estimates as of the 2020-03-20)

Estimate
New infections 21148 (14653 – 39569)
Expected change in daily cases Increasing
Effective reproduction no. 1.5 (1 – 2.1)
Doubling time (days) 8.5 (4.7 – 22)
Adjusted R-squared 0.78 (0.31 – 0.95)


Table 1: Latest estimates (as of the 2020-03-20) of the number of cases by date of infection, the expected change in daily cases, the effective reproduction number, the doubling time, and the adjusted R-squared of the exponential fit. The mean and 90% credible interval is shown for each numeric estimate.

Reported and estimated cases by date of onset and time-varying reproduction number estimates


Figure 2: A.) Cases by date of report (bars) and estimated cases by date of infection. B.) Time-varying estimate of the effective reproduction number. Light grey ribbon = 90% credible interval. Estimates are shown until the 2020-03-20.Dark grey ribbon = 50% credible interval. Confidence in the estimated values is indicated by shading with reduced shading corresponding to reduced confidence.

Time-varying rate of spread and doubling time


Figure 3: A.) Time-varying estimate of the rate of spread, B.) Time-varying estimate of the doubling time in days (note that when the rate of spread is negative the doubling time is assumed to be infinite), C.) The adjusted R-squared estimates indicating the goodness of fit of the exponential regression model (with values closer to 1 indicating a better fit). Estimates are shown until the 2020-03-20. Light grey ribbon = 90% credible interval; dark grey ribbon = the 50% credible interval. Confidence in the estimated values is indicated by shading with reduced shading corresponding to reduced confidence.

Regional Breakdown

Data availability

Limitations

Summary of latest reproduction number and case count estimates


Figure 4: Cases with date of infection on the 2020-03-20 and the time-varying estimate of the effective reproduction number (bar = 90% credible interval). Regions are ordered by the number of expected daily cases and shaded based on the expected change in daily cases. The dotted line indicates the target value of 1 for the effective reproduction no. required for control and a single case required for elimination.

Reproduction numbers over time in the six regions with the most cases currently


Figure 5: Time-varying estimate of the effective reproduction number (light grey ribbon = 90% credible interval; dark grey ribbon = 50% credible interval) in the regions expected to have the highest number of incident cases. Estimates are shown up to the 2020-03-20. Confidence in the estimated values is indicated by shading with reduced shading corresponding to reduced confidence. The dotted line indicates the target value of 1 for the effective reproduction no. required for control.

Cases with date of onset on the day of report generation in the six regions with the most cases currently


Figure 6: Cases by date of report (bars) and estimated cases by date of infection (light grey ribbon = 90% credible interval; dark grey ribbon = 50% credible interval) in the regions expected to have the highest number of incident cases. Estimates are shown up to the 2020-03-20.Confidence in the estimated values is indicated by shading with reduced shading corresponding to reduced confidence.

Reproduction numbers over time in all regions


Figure 7: Time-varying estimate of the effective reproduction number (light grey ribbon = 90% credible interval; dark grey ribbon = 50% credible interval) in all regions. Estimates are shown up to the 2020-03-20. Confidence in the estimated values is indicated by shading with reduced shading corresponding to reduced confidence. The dotted line indicates the target value of 1 for the effective reproduction no. required for control.

Cases with date of onset on the day of report generation in all regions

Figure 8: Cases by date of report (bars) and estimated cases by date of infection (light grey ribbon = 90% credible interval; dark grey ribbon = 50% credible interval) in all regions. Estimates are shown up to the 2020-03-20. Confidence in the estimated values is indicated by shading with reduced shading corresponding to reduced confidence.

Latest estimates (as of the 2020-03-20)

State New infections Expected change in daily cases Effective reproduction no. Doubling time (days)
Alabama 860 (216 – 1570) Unsure 1.8 (0.7 – 2.9) 7.3 (2.6 – Cases decreasing)
Alaska 149 (50 – 408) Likely increasing 1.8 (0.9 – 3.2) 6 (2.7 – Cases decreasing)
Arizona 896 (515 – 1673) Increasing 1.8 (1.4 – 2.2) 5.1 (3.4 – 9.4)
Arkansas 905 (483 – 2376) Increasing 2.2 (1.1 – 3.9) 4 (2.4 – 110)
California 5103 (4076 – 6851) Increasing 1.4 (1.3 – 1.7) 8 (4.9 – 62)
Colorado 2879 (1175 – 4311) Increasing 2 (1.2 – 3.1) 4.9 (2.9 – 14)
Connecticut 1957 (578 – 3989) Likely increasing 1.9 (0.8 – 3.1) 5.4 (2.6 – Cases decreasing)
Delaware 291 (180 – 433) Increasing 1.9 (1.4 – 2.3) 4.8 (3.2 – 11)
District of Columbia 414 (186 – 849) Likely increasing 1.7 (0.9 – 2.6) 6.3 (3.2 – Cases decreasing)
Florida 4690 (2422 – 6059) Increasing 1.8 (1.2 – 2.4) 5.6 (3.6 – 21)
Georgia 3062 (1813 – 4774) Increasing 1.7 (1.2 – 2.7) 6.3 (3.1 – 28)
Guam 97 (45 – 186) Increasing 2 (1.3 – 2.8) 4.9 (3 – 16)
Hawaii 173 (86 – 285) Likely increasing 1.6 (0.9 – 2.1) 6.1 (3.5 – Cases decreasing)
Idaho 343 (147 – 746) Increasing 2.2 (1 – 5) 5.1 (2.2 – Cases decreasing)
Illinois 3471 (2434 – 4727) Increasing 1.7 (1.2 – 2.1) 6.8 (4.2 – 31)
Indiana 1617 (1046 – 2418) Increasing 2.2 (1.4 – 2.8) 4.1 (2.6 – 8.6)
Iowa 362 (209 – 633) Increasing 2.1 (1.2 – 3.4) 4.5 (2.3 – 10)
Kansas 368 (118 – 1279) Increasing 2 (1.2 – 3.4) 5.1 (2.4 – 28)
Kentucky 482 (209 – 803) Increasing 1.7 (1.2 – 2.9) 5.8 (2.7 – Cases decreasing)
Louisiana 3652 (1329 – 5084) Likely increasing 1.6 (0.8 – 2) 8.2 (3.8 – Cases decreasing)
Maine 312 (163 – 574) Increasing 2 (1.3 – 3) 4.8 (2.9 – 15)
Maryland 1272 (528 – 2116) Likely increasing 1.8 (0.5 – 2.7) 5.6 (2.6 – Cases decreasing)
Massachusetts 3886 (3212 – 4661) Increasing 1.9 (1.6 – 2.3) 5.3 (4 – 8.8)
Michigan 5426 (3556 – 10171) Increasing 1.9 (1.2 – 2.8) 4.6 (3 – 13)
Minnesota 635 (344 – 1856) Increasing 1.7 (1.1 – 4) 6 (2.5 – 67)
Mississippi 1052 (606 – 1934) Increasing 2 (1.5 – 2.8) 4.5 (2.8 – 8.6)
Missouri 1058 (278 – 1502) Likely increasing 2 (0.6 – 2.6) 4.9 (2.6 – Cases decreasing)
Montana 162 (51 – 378) Likely increasing 1.8 (1 – 2.9) 5.7 (2.1 – Cases decreasing)
Nebraska 136 (61 – 205) Likely increasing 1.4 (1 – 1.7) 13 (5.1 – Cases decreasing)
Nevada 796 (503 – 1482) Increasing 1.7 (1.1 – 2.7) 6.3 (3.3 – 23)
New Hampshire 234 (122 – 338) Increasing 1.6 (1 – 2.3) 6.5 (3.1 – 32)
New Jersey 14060 (8768 – 20043) Increasing 2.1 (1.4 – 3.6) 4.4 (2.4 – 8.3)
New Mexico 287 (211 – 575) Increasing 2.1 (1.4 – 3.8) 5.1 (2.9 – 24)
New York 66926 (44466 – 101688) Increasing 1.8 (1.5 – 2.2) 5.1 (3.7 – 7.6)
North Carolina 1230 (724 – 2635) Likely increasing 1.8 (0.8 – 2.7) 5.8 (2.8 – 35)
North Dakota 103 (53 – 193) Increasing 1.9 (1.1 – 2.7) 5.6 (3.1 – 38)
Ohio 1441 (524 – 3671) Increasing 1.6 (1.1 – 2.6) 6.4 (3.2 – 76)
Oklahoma 548 (403 – 1224) Increasing 2.2 (1.5 – 2.8) 3.9 (2.4 – 7.7)
Oregon 626 (401 – 936) Increasing 1.8 (1.2 – 2.5) 5.5 (3.4 – 12)
Pennsylvania 2908 (1653 – 4591) Increasing 1.9 (1.2 – 2.6) 5.3 (3.2 – 16)
Puerto Rico 196 (50 – 377) Increasing 2.5 (1 – 3.8) 3.8 (2.1 – 16)
Rhode Island 285 (131 – 533) Increasing 1.8 (1.2 – 2.8) 5.8 (3.6 – 24)
South Carolina 1082 (661 – 2647) Increasing 2 (1.5 – 3.1) 4.7 (2.9 – 13)
South Dakota 88 (34 – 193) Likely increasing 1.7 (0.9 – 2.5) 5.9 (2.9 – Cases decreasing)
Tennessee 1792 (897 – 3969) Increasing 2 (1.1 – 4.1) 5.3 (2.7 – 72)
Texas 2262 (1514 – 3383) Increasing 1.7 (1.3 – 2.1) 6 (3.8 – 13)
Utah 677 (239 – 1146) Likely increasing 1.7 (0.8 – 2.6) 7.1 (3.2 – Cases decreasing)
Vermont 239 (163 – 313) Increasing 1.9 (1.2 – 2.3) 5.6 (3.2 – 17)
Virginia 789 (435 – 1185) Increasing 1.7 (1.2 – 2.3) 6.5 (3.4 – 38)
Washington 4476 (3340 – 6731) Increasing 1.4 (1.2 – 1.8) 9.1 (5.2 – 26)
West Virginia 124 (39 – 204) Increasing 2.1 (1 – 2.9) 4.5 (2.3 – 140)
Wisconsin 1262 (914 – 1772) Increasing 1.6 (1.2 – 1.9) 5.7 (3.8 – 11)
Wyoming 100 (49 – 163) Increasing 1.7 (1.1 – 2.2) 5.6 (3.1 – Cases decreasing)


Table 2: Latest estimates (as of the 2020-03-20) of the number of cases by date of infection, the effective reproduction number, and the doubling time in each region. The mean and 90% credible interval is shown.

“2019 Novel Coronavirus Covid-19 (2019-nCoV) Data Repository.” 2020. Johns Hopkins CSSE. https://github.com/CSSEGISandData/COVID-19.

Abbott, Sam, Joel Hellewell, James D. Munday, and Sebastian Funk. 2020. “NCoVUtils: Utility Functions for the 2019-Ncov Outbreak.” - - (-): –. https://doi.org/10.5281/zenodo.3635417.

Xu, Bo, Bernardo Gutierrez, Sarah Hill, Samuel Scarpino, Alyssa Loskill, Jessie Wu, Kara Sewalk, et al. n.d. “Epidemiological Data from the nCoV-2019 Outbreak: Early Descriptions from Publicly Available Data.” http://virological.org/t/epidemiological-data-from-the-ncov-2019-outbreak-early-descriptions-from-publicly-available-data/337.

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